If this fools them, why not pick a sunny day (shouldn't be an issue in Hotlanta, should it?) and try this trick again?

They can stroll around the city picking up canned goods, water, weapons, tools, etc.

If they're at the point where they absolutely have to, then it's probably an option. Until then, it's unnecessary and terrifying. Their camp isn't really a place for encountering/storing zombies, and I'm not sure how easy it is to isolate zombies to do that in the city.